Lubricant additives and production thereof



Patented Mar. 30, 1954 UNITED STATES TENT OFFICE LUBRICANT ADDITIVES AND PRODUCTION THEREOF ware No Drawing. Application October 31, 1951, Serial No. 254,188

14 Claims. (Cl. 260-609) The present invention relates to improvements in oil additives and processes for their production. It relates more particularly to detergent-antioxidant lubricating oil additives comprising alkyl phenol sulfides and their metal salts, and to improved methods for their preparation by which their corrosivity toward metals such as copper, silver, and their alloys is materially reduced.

As is well known in the art, alkyl phenol sulfides and their metal salt derivatives, such as magnesium, calcium, barium or strontium salts of tertiary amyl phenol sulfide and polysulfides, the salts of tertiary octyl phenol sulfides, disulfides, and the like, and related compounds, have proved to be very successful additives, especially for lubricating oils. Other salts, such as the tin or zinc salts, alone or mixed with the above salts can be used. They are also useful as additives in other liquid hydrocarbons, such as diesel and oil burner fuels and the like where the presence of detergents, sludge dispersers, antioxidants and the like is desirable. They have been used with particular success in mineral base lubricating oils for internal combustion engines. However, the alkyl phenol sulfides and metal salts thereof often have the objectionable feature of being fairly corrosive toward copper, silver, copper-lead alloys, and related metals and alloys which are widely used as bearing metals.

The above-mentioned corrosion tendencies are particularly serious in the case of alkyl phenol sulfide salts of metals other than barium. It has been found that basic-reacting barium compounds have the peculiar property of rendering non-corrosive the overactive or loosely bound sulfur present in the alkyl phenol sulfide whereas other such metal compounds, even of other alkaline earth metals, do not have this property.

A particular object of the present invention is to reduce this tendency toward corrosivity, which appears to be due to overactive or loosely bound sulfur. It has now been discovered that this condition may be considerably improved by changing the process of manufacturing this type of additive.

Additives of the phenol sulfide type have generally been prepared by the treatment of phenols, e. g., alkylated phenols such as tertiary amyl, tertiary octyl, and the like, with a sulfur chloride, followed by neutralization of the resulting phenol sulfide with a metallic base if desired. Both sulfur monochloride and sulfur dichloride may be used for the sulfurization of the phenols.

In accordance with the present invention, an additional step is employed in preparing the additives. The corrosive phenol sulfide is treated with an amount of basic reacting barium compound preferably insufficient to neutralize completely the phenol radical. The resulting partial barium salt is then hydrolyzed whereby the barium is substantially completely removed. The resulting alkyl phenol sulfide may then be used per se or may be converted to a metal salt derivative by the usual procedures. The treated phenol sulfides and their metallic salts will normally be sufficiently non-corrosive to pass specification corrosion tests when employed in a lubricating oil.

The sulfur chloride and alkyl phenol are reacted together at a moderate temperature preferably above about F. (70 to 212 F.), preferably in the range of to F. Sufiicient sulfur chloride will be used to form sulfides having from 1 to 4 or more sulfur atoms interconnecting benzene nuclei. Preferably, about 2 mols of the phenol to about 1.5 to 2.0 mole of sulfur chloride are used.

The phenol sulfide, which is usually prepared in a suitable solvent, e. g., a light hydrocarbon or chlorinated hydrocarbon such as ethylene dichloride, is then reacted with a basic reacting barium compound. Specific barium compounds include barium hydroxide pentahydrate, barium hydroxide octahydrate, barium oxide, barium carbonate, etc. This reaction may be conducted at elevated temperatures such as in the range of about to 300 F. or higher.

The amount of barium compound added may be varied over a rather wide range to achieve beneficial results. At least sufiicient material should be used to react with or otherwise render non-corrosive the overactive or loosely bound corrosive components of the sulfide. Generally, at least an equivalent of 0.1. mol of barium should be employed for each mol of OH radical in the alkyl phenol sulfide. The sulfide may be completely neutralized with the barium basic com.- pound, but this is generally undesirable from standpoints of cost, amounts of materials needed, and the like. Preferably, from 0.2 to 0.6 mol of barium per mol of -OH radical is used. Apparently, the basic barium material reacts with unstable, corrosive components in the sulfide with greater case than it does with the OH radical, and for this reason quantities insufficient to completely neutralize the phenol radical are usually adequate.

The partial barium salt so formed is then hydrolyzed under conditions whereby an alkyl phenol sulfide substantially free of barium is re-' formed. This may be done bytreatrnent with a mineral acid, preferably concentrated hydrochloric or sulfuric acid, in excess amounts at ordinary temperatures. The hydrolyzed material may then be treated to remove inorganic barium salts and excess acid. This may be done by water washing which may be carried out in batches, sufiicient washes being used to form a substantially neutral alkyl phenol sulfide. Preferably, warm or hot water is used. The treated alkyl phenol sulfide may then be stripped free of solvent.

Generally it is preferred to carry out the above treating and hydrolysis steps in an oil solution of the phenol sulfide. For example, the alkyl phenol sulfide, stripped free of solvent, is dissolved in a lubricating oil base stock having a viscosity in the range of about 35 to 75 seconds Saybolt at 210 F. and is then treated with the barium compound and hydrolyzed as heretofore described.

If it is desired to prepare a metal salt derivative of the treated and hydrolyzed sulfide, it may be neutralized, preferably in oil solution, with a metal compound such as finely divided oxide, bydroxide, hydride, alkoxide or other basic neutralizing agent. Such agents include the alkaline earth metal compounds, e. g. of calcium, barium, magnesium, etc., or derivatives of monovalent metals such as sodium, potassium and lithium or of polyvalent metals such as nickel, cobalt, tin, lead, zinc, copper, cadmium, manganese, chromium, etc., or any combination of these metal compounds may be used. This reaction is generally carried out at temperatures in the range of about 175 to 300 F. for several hours with stirring whereby water is removed. The material may then be filtered to remove excess neutralization agent, and an oil concentrate, containing for example 20 to 50% of the metal salt, is recovered for use.

Although this invention has particular application to the preparation of non-barium metal salts, substantial improvements are realized by employing the intermediate treating and hydrolyzing step prior to the manufacture of finished barium salts and particularly prior to making mixed metal salts including barium, such as barium-calcium salts.

The invention will be more fully understood by reference to the following specific examples.

Example I.Preparation of products Product A.--Sulfur dichloride (1.6 mols) was added slowly to 2.0 mols of tert.octyl phenol dissolved in ethylene dichloride solvent at a temperature of about 86 F. The reaction mixture was refluxed free of HCl vapors, filtered and stripped free of solvent. The resulting product contained the equivalent of about 1.6 sulfur atoms interconnecting two benzene nuclei. A 50% concentration of the product in an oil base having a viscosity of about 150 seconds (Saybolt) at 100 F. was prepared (product A).

Product B.600 grams of product A (50% concentrate) blended with an additional 450 grams of the same oil base was agitated and heated to a temperature of about 250 F. 89.3 grams of barium hydroxide octahydrate (equivalent to about 0.22 mol barium per mol -OI-I in the sulfide) was added while the mixture was blown with nitrogen to remove water. 500 grams of the resulting salt-oil solution, containing 3.1 weight per cent barium, was blended with 500 grams of hexane to reduce viscosity and treated with 150 grams of concentrated HCl solution. The hydrolyzed material was water washed until substantially neutral, stripped free of hexane sol- 4 vent, and upon analysis was found to contain no barium.

Product 02-300 grams of product B (oil-sulfide concentrate) was treated with 30 grams of hydrated lime, in the presence of 22 grams of 91% isopropyl alcohol at a temperature of 140 F. The resulting calcium salt-oil solution was filtered through Hy-flo diatomaceous filter aid and analysis showed 1.84 weight per cent calcium.

Product D.-An oil solution of tert.-octyl phenol sulfide, prepared in substantially the same manner as product A was directly neutralized with hydrated lime using the procedure employed in making product C. The filtered material contained 1.98 weight per cent calcium.

Product E.-An oil solution of tert.-octyl phenol sulfide (150 grams of each), prepared in accordance with the procedure used in preparing product A, was blended with an additional 225 grams of oil and treated directly with 7.0 grams of hydrated lime (equivalent to about 0.180 mol calcium per mol of OI-I radical) in the presence of alcohol. The material contained 0.7 weight per cent calcium and was then hydrolyzed and water washed by the procedures used to prepare Product B. The hydrolyzed product contained no calcium.

Example II.-Corrosion tests The products of Example I were tested by copper and silver corrosion tests. The copper corrosion test used was a modification of the C. R. C. method, 11-16-445, in which a polished metallic copper strip is immersed in the oil to be tested for a period of three hours at 210 F. and then noting the extent of staining. Ratings are given on a scale of from 1 to 10 which denotes discoloration ranging from no stain to a black surface film.

The silver corrosion test involved measuring the weight change and observing the discoloration of a sterling silver strip immersed in cc. of the test oil for 17 hours at 325 F. Stain is rated from 0 (no discoloration) to 8 for a complete sulfide film. A DNP (did not pass) rating is given where stain and/or weight changes are excessive.

Blends were prepared containing 1.0 weight per cent of the active ingredient of each of the products in both a diesel-type lubricant having a viscosity of about 900 S. S. U. at F. (for the silver corrosion test) and a solvent extracted Mid-Continent base oil having a viscosity of about 37 S. S. U. at 210 F. (for the copper corrosion test). The blends were tested and the fol lowing results were obtained:

The alkyl phenol sulfide treated with barium hydroxide and hydrolyzed was significantly less corrosive than the untreated alkyl phenol sulfide. The calcium salt derivative of the barium treated and hydrolyzed material was considerably less corrosive than either the calcium salt made directly by conventional procedures or the lime treated and hydrolyzed material.

The method of the present invention applies generally to derivatives of any alkylated phenol or mixtures thereof. Such phenols may contain one or more alkyl groups, and these groups may vary in chain length from one to about carbon atoms. Preferably, at least 4 and not more than 20 carbon atoms are present in at least one alkyl group. Typical alkyl groups which may be present are n-butyl, tert.-butyl, tert-amyl, n-hexyl, tert.-octyl, n-decyl, cetyl, stearyl, and wax-alkyl groups. Cycloaliphatic groups may also be presout.

By using the intermediate treating and hydrolysis steps, corrosivity towards both copper and silver is substantially eliminated in the concentration most commonly used in lubricating oils (0.01 to 5% or 10% by weight of active ingredient based on the total weight of the oil). For heating oils, diesel fuels, and the like, the proportions to be employed are ordinarily much smaller than in lubricating oils, being of the order of 0.002 to 0.1% by weight. understood that either the alkyl phenol sulfide per se or the metal salt derivative may be used as an additive after treatment, although the salts are usually preferred when detergency characteristics of the oil are to be improved.

It will be understood also that the additives of the present invention may be used either alone or with other additives such as antioxidants, metal deactivators, oil soluble petroleum sulfonotes, etc., in various hydrocarbon or basically hydrocarbon oils, including automotive fuels, diesel fuels, heating fuels, distiliatee, lubricating oils, and the like as will be self-evident to those skilled in the art.

What is claimed is:

1. An improved, substantially non-corrosive additive composition for use in hydrocarbon oils and the like selected from the group consisting of alkyl phenol sulfides and the metal salt derivatives thereof, said sulfide being treated, prior to use, with a basic reacting barium compound and hydrolyzed to form a substantially barium-free alkyl phenol sulfide.

2. An improved, substantially non-corrosive additive composition for use in hydrocarbon oils and the like selected from the group consisting of alkyl phenol sulfides and the metal salts thereof, said sulfide being formed by treating an alkyl phenol with a sulfur chloride whereby a product having from about 1 to 4 sulfur atoms intercon- I necting benzene nuclei is formed, further treating the resulting product with an amount of a basic reacting barium compound insufficient to completely neutralize same, and hydrolyzing the barium derivative.

3. Composition according to claim 2 wherein said amount of the barium compound is equivalent to at least 0.1 mol barium per mol of OH radical in said alkyl phenol sulfide.

4. Composition according to claim 3 wherein said amount is in the range of 0.2 to 0.6 mol per mol of said OI-I radical.

5. The process of reducing the corrosiveness of alkyl phenol sulfides and their metal salts which comprises the steps of treating said sulfide It is to be with a basic reacting barium compound and then hydrolyzing the treated material.

6. Process according to claim 5 wherein an amount of said basic reacting compound equivalent to at least 0.1 mol barium per mol of Ol-I radical in said sulfide is employed.

7. The process of preparing a phenol sulfide low in loosely combined or active sulfur which comprises reacting an alkyl phenol with suficient sulfur chloride at a temperature above about F. to form a product having in the range of about 1 to 4 sulfur atoms interconnecting benzene nuclei, treating the product with an amount of a basic reacting barium compound insufiicient to completelyneutralize same, and hydrolyzing the partially neutralized material to form a substan-- tially barium-free product.

8. In the process of producing allay phenol sulfides and their metal salt derivatives which includes the steps of reacting an allzyl phenol with a sulfur chloride at a temperature above about 70 F. to form allryl phenol sulfide, the improvement which comprises further treating the resulting phenol sulfide with an amount or a basic reacting barium compound equivalent to at least 0.1 mol barium per mol of Ol-I radical in said sulfide and hydrolyzing the treated material whereby a substantially non-corrosive product is formed.

9. In as process of producing alkyl phenol sulfides and their alkaline earth metal salts in which alkli'l phenol sulfide is prepared by reacting about 2 mole of an alkyl phenol having 4 to 20 carbons in at least one alkyl group with from 1.5 to 2.0 mole of a sulfur chloride at a temperature in the range of about 70 to 212 F. and wherein the resulting product is corrosive, the improvement which comprises treating the resulting sulfide with a basic reacting barium compound e uivalent to at least 0.1 mol barium per mol of OH radical in said phenol, hydrolyzing the treated material to remove barium therefrom and recovering an alky1 phenol sulfide substantially non-corrosive to metals.

10. A process as in claim 9 wherein the amount of said barium compound is in the range oi 0.2 to 0.6 mol barium per mol of said -OH radical.

11. A process as in claim 9 wherein said barium compound is a barium hydroxide.

12. A process as in claim 9 wherein said alkyl phenol is tertiary-octyl phenol.

13. A process as in claim 9 wherein said substantially non-corrosive product is treated with hydrated lime in the presence of isopropyl alcohol to produce the calcium salt thereof.

1 A process as in claim 9 wherein said treated alkyl phenol sulfide is hydrolyzed by a mineral acid and water Washed to remove inorganic hydrolysis products.

JESSE S. WEISSBERG. JOHN R. JONES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,362,289 Mikeska Nov. 7, 1944 2,409,303 Morris et al. Oct. 15, 1946 2,461,335 Mikeska Feb. 8, 1949 2,581,919 Albert Jan. 8, 1952 

1. AN IMPROVED, SUBSTANTIALLY NON-CORROSIVE ADDITIVE COMPOSITION FOR USE IN HYDROCARBON OILS AND THE LIKE SELECTED FROM THE GROUP CONSISTING OF ALKYL PHENOL SULFIDES AND THE METAL SALT DERIVATIVES THEREOF, SAID SULFIDE BEING TREATED, PRIOR TO USE, WITH A BASIC REACTING BARIUM COMPOUND AND HYDROLYZED TO FORM A SUBSTANTIALLY BARIUM-FREE ALKYL PHENOL SULFIDE. 